1. Technical Field
The present invention relates generally to communications within a client-server computer network and, in particular, to a method of routing client requests to specified server objects using a server resource-to-IP port mapping scheme.
2. Description of the Related Art
The World Wide Web is the Internet""s multimedia information retrieval system. In the Web environment, client machines effect transactions to Web servers using the Hypertext Transfer Protocol (HTTP), which is a known application protocol providing users access to files (e.g., text, graphics, images, sound, video, etc.) using a standard page description language known as Hypertext Markup Language (HTML).
It is known in the art to collect multiple servers in a xe2x80x9cpoolxe2x80x9d so that the servers may be managed collectively. All of the servers may have a common Uniform Resource Locator (URL) from the perspective of a client machine running a browser. These servers typically support many different types of server objects (e.g., databases, CGI scripts, active server page (.asp) scripts, and the like) that are desired to be accessed by the client machines.
The set of servers in the pool get HTTP requests from Web browser clients, and these requests reference server resources (e.g., one or more databases supported on or across those servers). It is desired to route these HTTP requests to the appropriate server in the server pool and to maintain balanced loads across the servers. Not all servers in the cluster, however, are equal (i.e. they are not homogeneous, with respect to their server resource objects). For example, the requested database may reside on one or more than one server, but not necessarily on all servers.
To route the request, the name of the requested database, which is part of the HTTP packet, must be known. This name is commonly extracted by parsing the HTTP request in a two-step process. In particular, the received TCP/IP packets (that include the HTTP request) are first parsed or xe2x80x9copened upxe2x80x9d by TCP/IP services to determine the application that will process the request. The request is then passed to the application to be further processed, i.e. to determine the requested object. These processing requirements have a negative impact on the overall performance of servicing the client request.
It would be advantageous to be able to determine the name of the server resource without having to parse the TCP/IP packet, and then parse (and possibly decrypt) the HTTP packet.
The present invention addresses this problem.
The object of this invention is a means and method for mapping server resource objects to the servers that provide access to these resource objects, preferably using a set of TCP/IP port numbers. Through dynamically generated HTML, Web pages are delivered to Web clients. These Web pages contain anchors for these server resource objects. The underlying anchors are preferably of the form:
http:// less than server name greater than : less than port greater than / less than server resource greater than 
where  less than server name greater than  maps to the IP address for a Resource Router and the port maps to the requested server resource. The Resource Router listens for TCP/IP requests coming in on the port set that map the server objects. When a request arrives at a port, the Resource Router fields the request, selects the xe2x80x9cbest providerxe2x80x9d and redirects or forwards the request to that server. The routing and redirection is based upon the port for the incoming request.
The Resource Router maintains a mapping of server objects to TCP/IP ports in the port space for the IP address under which is operates. This mapping is a table with a row for each server object. Preferably, the contents of the row are a port number, a server object, and a list of servers which are capable of serving the requested object. The list of servers is preferably ordered, based on a pre-specified criteria, so that the server best matching the specified criteria receives the request. The request is either forwarded to the server by the Resource Router, or a redirection response specifying the server is returned to the client, which in turn, redirects the response to the server.
The foregoing has outlined some of the more pertinent objects and features of the present invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention as will be described. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the following Detailed Description of the Preferred Embodiment.